Tool fixture

ABSTRACT

An opened-ended, four-sided structure for slidably retaining the tool therewithin, with a pilot dowel pin fixed to an end of the structure and extending therefrom into the structure. The pin is slidably received by a cylinder. The cylinder has pressured fluid inlet and vent ports in the wall thereof, and an external terminal end of the cylinder abuts a surface of the tool. The pin cooperates with an annular sleeve disposed about a portion of the inner cylinder wall to seal off the vent port until the cylinder, under pressured-fluid force, travels a predetermined distance to effect a tool movement stroke. Toward the end of the stroke, the vent port is uncovered and evacuates fluid from the cylinder.

United States Patent Ottestad 1 1 Feb. 6, 1973 TOOL FIXTURE FOREIGNPATENTS OR APPLICATIONS [76] Inventor: Jack B. Ottestad, 1442 Muirlancls1,333,104 6/1963 France ..91/402 Drive, La .lolla, Calif. PrimaryExaminer-Paul E. Maslousky [22] Att0rney Frank s. Troidl, David w.Tibbott and [21] Appl. No.: 79,596 Bernard J. Murphy 52 us. Cl. ..91/216R, 91/402 [57] ABSTRACT [51] Int. Cl. ..F0lb15/00,F15b 15/22 Anopened-ended, four-sided structure for slidably [58] Field of Search..91/402, 216 R, 216 A, l 17; retaining the tool therewithin, with apilot dowel pin 269/25, 46 fixed to an end of the structure andextending therefrom into the structure. The pin is slidably [56]References Cited received by a cylinder. The cylinder has pressuredfluid inlet and vent ports in the wall thereof, and an UNlTED STATESPATENTS external terminal end of the cylinder abuts a surface 2,882,7604/1959 Leifer ..91/216 R of the tool The P cooperates with an annularSleeve 2,947,275 8/1960 Ed d disposed about a portion of the innercylinder wall to 2,396,787 3/1946 Hawthorne etal. ..91/402 seal off thevent port until the cylinder, under pres- 2,546,904 3/1951 Nelius..91/216 R sured-fluid force, travels a predetermined distance to2,673,072 5/1954 Verderber 91/216 R effect a tool movement stroke.Toward the end of the 2,816,608 12/1957 Farmwold et a1. ..91/216 RStroke, the vent port is uncovered and evacuates fluid from thecylinder.

17 Claims, 6 Drawing Figures 28 54 72 r so 24 3 4O 4 tam-13? 4a e2--'--;t- 56 v 70, 4: 44 7O|J| 4 7 1 32 h J I l |4' i 14 j PATENTEDFEBBIQTS 3,714,866 SHEET 10F 2 Q INVENTOR J JACK 8. 07755740 AGENT PATENTEDFEB 6 I975 6 6 8 4 l 7 3 2 6 M 6 2 I- IE... w my 4\ mu 6 a? A 4 4 W 2 5M 5 5 3 Q 4 M I O 7. 4 O W '1 I p 2 6 2 8 5 0 a 4 a 6 H FIG. 4

FIG. 6

INVENTOR JACK 5. 07755740 AGENT Tool. FIXTURE This invention pertains toa fixture for supporting a fluid-powered tool for the address thereof toa workface, and in particular to such a tool supporting fixture which isfluid-powered for moving the tool a predetermined distance with meansautomatically operative for venting the enabling fluid, when the toolhas been moved said predetermined distance, to halt both tool movementand operation.

In the prior art it is known for fixtures to support tools and advancethem under the influence of fluid power. However, known devices of thistype have to be manually controlled, either to effect the movement ofthe tool, to vent the fluid which operates the fixture, or both.

It is an object of this invention to teach a fluidpowered tool-movingfixture having means for supporting the tool; means for engaging asurface of said tool for moving the tool in a given direction, having afluidpressure bearing surface and being movable in said given directionin response to a fluid pressuring of said bearing surface; and meanscoupling said surface-engaging means and said tool-supporting meanstogether, wherein said coupling means comprises means which pilot themovement of said engaging means along said given direction; saidengaging means has port means for admitting pressured fluid to saidbearing surface and for venting fluid therefrom; and said pilot meansand said engaging means cooperate to prevent venting of fluid from saidbearing surface until said engaging means has traveled a predetermineddistance in said direction and cooperatively and automatically ventfluid from said bearing surface, via said port means, when said engagingmeans has traveled said predetermined distance.

A feature of this invention comprises an open-ended, four-sidedstructure for slidably retaining a tool therewithin with a dowel-pinfixed to an end of the structure and extending therefrom into thestructure. The dowel-pin slidably receives a cylinder which cylinder hasfluid inlet and vent ports in the wall thereof and one end of thecylinder abuts a surface of the tool to effect tool movement. Thedowel-pin cooperates with an annular sleeve replaceably disposed in agiven position about a portion of the inner cylinder wall to seal offthe vent port until the piston has traveled a predetermined distance.

Further objects and features of this invention will become more apparentby reference tothe following description taken in conjunction with theaccompanying figures in which:

FIG. 1 is a top view of the fixture according to the invention showing atool disposed therewithin;

FIG. 2 is a side elevation .of the fixture and tool of FIG. 1, with aportion cut away showing, in vertical cross-section, the dowel-pin andcylinder as associated at the start of an operational stroke; and

FIG. 3 is a front elevational view, partly in cross section, taken alongsection 33 of FIG. 1, showing the dowel-pin and cylinder relationship atthe end of an operational stroke;

FIG. 4 is a view like that of FIG. 3 showing fluid supply and vent portsfor a tool operating means through communicating with the cylindersupply and vent ports;

FIG. 5 is a schematic representation of the fixture and tool arrangementof FIG. 4; and

FIG. 6 is a schematic representation of an alternate fixture and toolarrangement according to the invention.

As shown in FIG. 1 and 2 the fixture 10 comprises means for supporting atool for movement, and includes a structure 12 having side walls 14 and14, rear wall elements 16, and front wall elements 18. The tool 20, hereshown only in part, is a fluid-powered impact ram.

The tool 20, the impact ram only partly shown, is substantiallyidentical to the impact ram automatically and cyclically operated inaccordance with the teachings of my co-pending patent application Ser.No. 695,194, for Control Means for Fluid-powered Devices, filed Jan. 2,1968. The only difference of significance, between tool and thatdisclosed in the afore-mentioned pending application is that in tool 20the end cap presents two pair of fluid intake and discharge ports, andthe pertinence thereof to this invention is explained in the ensuringtext.

The tool 20 is slidably restrained within the fixture 10 by means ofslide bearings 22 carried by the fixture internally of the walls 14 and14', and elements 16 and 18. A cylinder 24 disposed within a raisedpocket 26 formed in side wall 14 receives a dowel-pin 28. Dowel pin 28depends from a horizontal web 30 arranged across the top of pocket 26and slidably receives cylinder 24 thereon pin 28 comprises means forcoupling together the tool moving cylinder 24 and the tool-supportingstructure 12. A lower closed end 32 of cylinder 24 abuts a surface 34 ofthe tool, the surface being presented by a horizontal rib 36 on the toolcasing.

As shown in FIG. 3, cylinder 24 has a fluid inlet port 38 and a fluidoutlet port 40 formed the wall thereof, said ports being exposed tocommunicate with a chamber 42. The chamber 42 is formed by a fluidbearing surface 44 which defines the inner bounds of a cavity 46 formedin cylinder 24, the surface 44 being spaced from dowel-pin 28.

As the dowel-pin 28 is fixed to the structure 12, pressurization ofsurface 44 causes the cylinder 24 to move relative to the dowel-pin 28.Such presurization is effected by communication of port 38 with apressured fluid top off port 48 of the tool 20 which is alignedtherewith. However, at the start of the stroke (FIG. 2) port 40 issealed off by dowel-pin 28 and a sleeve 50 disposed between thedowel-pin and the surface 44. Until cylinder 24 has traveled so far asto move sleeve 50 beyond port 40, the cavity 46 cannot be vented. Whenport 40 is uncovered by sleeve 50 the movement of the tool 20 bycylinder 24 is terminated; the pressured fluid is vented through acommunication of port 40 with a fluid exhaust port 52 of the tool whichis aligned therewith. Thereafter the fluid supply to the cylinder (andto the tool 20) is cut off (by control means not shown) and the tool 20can be slid back into a start position in the structure 12.

Sleeve 50 is replaceably retained in cylinder 24 by means of a retainingring 54, and the abutting of the inner end thereof against a shoulder 56formed in cylinder 24.

Cylinder 24 is constrained against the tool 20 by the fastening of walls14 and 14' to the sides of the tool by assembly bolts 58 and nuts 60.Thus, the enclosure of the cylinder within the pocket 26, and within thestructure as a whole, cooperates with dowel pin 28 to guide movement ofthe cylinder relative to thestructure. O- ring seals arranged in atool-facing surface of cylinder 24 seal the ports 38 and 40 to theprovisioned pressured-fluid supply and venting means, respectively.These latter are shown to be the fluid tap-off port 48 and the fluidexhaust port 52 of tool 20.

Tool 20 can be any fluid-powered tool having first fluid intake anddischarge ports 62 and 64, respectively, as shown in FIG. 3, forenabling a pressured fluid operation of the tool, which ports 62 and 64communicate (by means not shown here) with ports 48 and 52,respectively. Accordingly, as the tool 20 is moved relative to thefixture to the position shown in FIG. 3, such positioning will halt theoperation of the tool. Tool operation halts in that the enabling supplyof fluid is vented through cavity 46, ports 40 and 52, and finally port64. Of course, until port 40 is uncovered, tool operation, and toolmovement within fixture l0, occur simultaneously; they ceasesimultaneously also.

My novel fixture 10 is especially suitable for use with fluid-poweredtools such as the impact ram described in he afore-mentioned patentapplication Ser. No. 695,l94, and more so with such a ram being deployedin a paving breaker usage. Thus, I show my fixture walls 14 and 14' ascomprising a pair of gussets 66 with bore holes 68 therein for mountingof my fixture 10 to an ancillary machine--such as backhoe, for instance.

Finally, for purposes of illustration, tool ports 62 and 64 are shown asbeing coupled to lines or hoses 70 and 70'. In that the tool carries theports 62 and 64 and any such coupled hoses 70 and 70' therewith, as itslides on bearings 22, the fixture 10 has a raised pocket 26' in sidewall l4'.with a relief or slot 72 therein to accommodate the travel ofhoses 70 and 70 therealong.

FIGS. 4 and 5 more clearly illustrate the use of the fixture 10 forcontrolling tool movement and tool operation as well. With reference toFIG. 4, it will be seen that a tool operating means 74 is confinedwithin tool'20, and such means contemplate that disclosed in myco-pending application Ser. No. 695,194, or equivalent means.Accordingly, means 74 is responsive to pressured fluid, supplied viaintake port 62, to operate the tool 20. Discharge port 64 dischargesfluid from means 74. As FIGS. 4 and 5 show, the fluid supply providedvia port 62 is communicated with the cylinder 24 through means 74 andports 38 and 48. POrts 40 and 52 are also in communication with port 64through means 74. As long as port 40 is sealed off, means 74 willoperate the tool 20. When port 40 is uncovered, the pressured fluidsupply at port 62 is effectively shunted through the novel fixture l0and its cylinder 24, and tool operation halts.

While I have described my invention in connection with a specificembodiment thereof it is to be clearly understood that this is done onlyby way of example and not as a limitation to the scope of my inventionas seen in the objects thereof and in the accompanying claims. Forinstance, it is not at all necessary, as FIG, 6 illustrates, that thefixture enabling fluid be communicated through the tool itself. Itis'sufficient, to practice my invention, to fluid-couple my novelfixture, and the cylinder 24 thereof, with single inlet and vent ports62 and 64, respectively, of a given tool. This arrangement, shownschematically in FIG. 6, provides a parallel operation of the fixturewith the toolas long as port 40 is sealed off, and a serial arrangement,through which the tool-enabling fluid is shunted via the fixture, whichhalts both movement of the tool by the fixture and operation of the toolsimultaneously.

I claim:

1. A fluid-powered fixture for supporting a tool for movement,comprising:

means for slidably supporting the tool;

means for abuttingly engaging a surface of said tool,

for slidably moving said tool relative to said supporting means, havinga fluid-pressure bearing surface, and being movable in response to afluid pressuring of said bearing surface; and

means coupling said surface-engaging means and said tool-supportingmeans together; wherein said coupling means comprises guide means which,cooperative with said supporting means, guides the movement of saidengaging means;

said engaging means has port means for admitting pressured fluid to saidbearing surface and for venting fluid therefrom; and

said guide means and said engaging means cooperate to prevent venting offluid from said bearing surface until said engaging means has traveled apredetermined distance, and cooperatively and automatically vent fluidfrom said bearingsurface, via said port means, when said engaging meanshas traveled said predetermined distance.

2. A fixture, according to claim 1, wherein:

said engaging means comprises a cylinder, having an external surfacedisposed for effecting said abutting engagement with said tool surface,and an elongated, walled cavity formed therein and enclosed at one endonly;

said port means comprising an inlet port and a vent port formed throughthe wall of said cavity;

said guide means comprises a dowel-pin fixed at one end thereof to saidtool supporting means and projecting therefrom into said cavity;

said cylinder further having sealing means disposed within said cavitycooperative with said dowel pin to close off said vent port.

3. A fluid-powered fixture for supporting a tool for movement,comprising:

means for slidably supporting the tool;

,means for engaging a surface of said tool, for slidably moving saidtool relative to said supporting means, having a fluid-pressure bearingsurface, and being movable in response to a fluid pressuring of saidbearing surface; and

means coupling said surface-engaging means and said tool-supportingmeans together; wherein said coupling means comprises guide means which,cooperative with said supporting means, guides the movement of saidengaging means;

i said engaging means has port means for admitting pressured fluid tosaid bearing surface and for venting fluid therefrom; and

said guide means and said engaging means cooperate to prevent venting offluid from said bearing surface until said engaging means has traveled apredetermined distance, and cooperatively and automatically vent fluidfrom said bearing surface, via said port means, when said engaging meanshas traveled said predetermined distance; wherein said engaging meanscomprises a cylinder, having an external surface disposed for abuttingengagement with said tool surface, and an elongated, walled cavityformed therein and closed at one end only;

said port means comprises an inlet port and a vent port formed throughthe wall of said cavity;

said guide means comprises a dowel-pin fixed at one end thereof to saidtool supporting means and projecting therefrom into said cavity;

said cylinder further has sealing means disposed within said cavitycooperative with said dowel pin to close off said vent port; and

said sealing means comprises a sleeve interposed between said dowel-pinand said cavity wall.

4. A fixture, according to claim 3, wherein:

said supporting means comprises an open-ended,

quadrilateral structure having means for slidably retaining said tooltherewithin.

5. A fixture, according to claim 4, wherein:

said retaining means comprises slide-bearing-surfaced elements carriedon internal surfaces of said structure.

6. A fixture, according to claim 3, further including:

a replaceable retaining ring, carried by said piston,

holding said sleeve in position.

7. A fixture, according to claim 3, wherein:

said sleeve has a bore-hole formed through a side thereof, saidbore-hole being in throughgoing, communicating alignment with said ventport.

8. A fixture, according to claim 5, wherein:

said structure has a pair of gussets extending in parallel therefrom tofacilitate a coupling of said structure to an ancilliary machine ordevice.

9. In combination with a tool having pressured-fluid discharging andintake ports, a fluid-powered fixture for supporting and automaticallymoving the tool, comprising:

an open-ended structure for slidably supporting the tool;

means for engaging a surface of said tool, for slidably moving said toolrelative to said structure, having a fluid-pressure bearing surface, andbeing movable in response to a fluid pressuring of said bearing surface;and

means coupling said surface-engaging means and said structure together;wherein said coupling means comprises guide means which,

cooperative with said structure, guides the movement of said engagingmeans;

said engaging means includes means for admitting pressured fluid to saidbearing surface, and means for venting fluid therefrom, said fluidadmitting means being in throughgoing communication with said intakeport, and said fluid venting means being in throughgoing communicationwith said discharging port; and

said guide means and said engaging means cooperate to prevent venting offluid from said bearing surface until said engaging means has traveled apredetermined distance, and cooperatively and automatically vent fluidfrom said bearing surface,

via said fluid venting means, when said engaging means has traveled saidpredetermined distance. 10. a fixture, according to claim 9, wherein:

5 said engaging means comprises a cylinder having an external surfacedisposed for abutting engagement with said tool surface, and anelongated, walled cavity formed therein and closed at one end only;

said admitting means and said venting means comprise an inlet port and avent port, respectively, formed through the wall of said cavity;

said guide means comprises a dowel-pin fixed at one end thereof to saidstructure and projecting therefrom into said cavity;

said cylinder further having sealing means disposed within said cavitycooperative with said dowel-pin to close off said vent port.

1 1. A fixture according to claim 10, wherein:

said sealing means comprises a sleeve interposed between said dowel-pinand said cavity wall.

12. A fixture, according to claim 11, further includa replaceableretaining ring, carried by said cylinder,

holding said sleeve in position. I 13. A fixture, according to claim 11,wherein: said sleeve has a bore-hole formed through a side thereof, saidbore-hole being in throughgoing,

communicating alignment with said vent port.

14. A fixture, according to claim 9, wherein:

said structure comprises slide-bearing-surfaced elements carried oninternal surfaces thereof for slidably retaining said tool therebetween.

15. A fixture, according to claim 14, wherein:

said structure has a pair of gussets extending in parallel therefrom tofacilitate a coupling of said structure to an ancilliary machine ordevice.

16. In combination with a fluid-powered tool having first meanssupplying pressured fluid thereto for enabling tool operation and secondmeans for venting fluid therefrom, a fluid-powered fixture for movingthe tool and for controlling tool operation, comprising:

means for engaging a surface of said tool;

said engaging means having a bearing surface responsive to a fluidpressuring thereof to cause movement of said engaging means and, as aresult, to effect movement of said tool;

means interconnecting said first means with said bearing surface andproviding a first fluid communication therebetween;

means effective for interconnecting said second means with said bearingsurface for providing a second fluid communication therebetween; andguide means fixed against movement, relative to said engaging means, forguiding movement of said engaging means and effective, in a first fixedposition, relative to and coincident with movement of said engagingmeans, for interdicting said second fluid communication, and effectivein a second fixed position relative to said engaging means upon movementof the latter, for automatically accommodating said second fluidcommunication, said guide means guiding movement of said engaging meansand enabling an operation of said tool when said guide means is in saidfirst relative position, and halting said movement and operation whensaid guide means is in said second relative position.

17. A fixture, according to claim 16, wherein: said engaging meansfurther includes means for supporting said tool.

1. A fluid-powered fixture for supporting a tool for movement,comprising: means for slidably supporting the tool; means for abuttinglyengaging a surface of said tool, for sliDably moving said tool relativeto said supporting means, having a fluid-pressure bearing surface, andbeing movable in response to a fluid pressuring of said bearing surface;and means coupling said surface-engaging means and said toolsupportingmeans together; wherein said coupling means comprises guide means which,cooperative with said supporting means, guides the movement of saidengaging means; said engaging means has port means for admittingpressured fluid to said bearing surface and for venting fluid therefrom;and said guide means and said engaging means cooperate to preventventing of fluid from said bearing surface until said engaging means hastraveled a predetermined distance, and cooperatively and automaticallyvent fluid from said bearing surface, via said port means, when saidengaging means has traveled said predetermined distance.
 1. Afluid-powered fixture for supporting a tool for movement, comprising:means for slidably supporting the tool; means for abuttingly engaging asurface of said tool, for sliDably moving said tool relative to saidsupporting means, having a fluid-pressure bearing surface, and beingmovable in response to a fluid pressuring of said bearing surface; andmeans coupling said surface-engaging means and said tool-supportingmeans together; wherein said coupling means comprises guide means which,cooperative with said supporting means, guides the movement of saidengaging means; said engaging means has port means for admittingpressured fluid to said bearing surface and for venting fluid therefrom;and said guide means and said engaging means cooperate to preventventing of fluid from said bearing surface until said engaging means hastraveled a predetermined distance, and cooperatively and automaticallyvent fluid from said bearing surface, via said port means, when saidengaging means has traveled said predetermined distance.
 2. A fixture,according to claim 1, wherein: said engaging means comprises a cylinder,having an external surface disposed for effecting said abuttingengagement with said tool surface, and an elongated, walled cavityformed therein and enclosed at one end only; said port means comprisingan inlet port and a vent port formed through the wall of said cavity;said guide means comprises a dowel-pin fixed at one end thereof to saidtool supporting means and projecting therefrom into said cavity; saidcylinder further having sealing means disposed within said cavitycooperative with said dowel pin to close off said vent port.
 3. Afluid-powered fixture for supporting a tool for movement, comprising:means for slidably supporting the tool; means for engaging a surface ofsaid tool, for slidably moving said tool relative to said supportingmeans, having a fluid-pressure bearing surface, and being movable inresponse to a fluid pressuring of said bearing surface; and meanscoupling said surface-engaging means and said tool-supporting meanstogether; wherein said coupling means comprises guide means which,cooperative with said supporting means, guides the movement of saidengaging means; said engaging means has port means for admittingpressured fluid to said bearing surface and for venting fluid therefrom;and said guide means and said engaging means cooperate to preventventing of fluid from said bearing surface until said engaging means hastraveled a predetermined distance, and cooperatively and automaticallyvent fluid from said bearing surface, via said port means, when saidengaging means has traveled said predetermined distance; wherein saidengaging means comprises a cylinder, having an external surface disposedfor abutting engagement with said tool surface, and an elongated, walledcavity formed therein and closed at one end only; said port meanscomprises an inlet port and a vent port formed through the wall of saidcavity; said guide means comprises a dowel-pin fixed at one end thereofto said tool supporting means and projecting therefrom into said cavity;said cylinder further has sealing means disposed within said cavitycooperative with said dowel pin to close off said vent port; and saidsealing means comprises a sleeve interposed between said dowel-pin andsaid cavity wall.
 4. A fixture, according to claim 3, wherein: saidsupporting means comprises an open-ended, quadrilateral structure havingmeans for slidably retaining said tool therewithin.
 5. A fixture,according to claim 4, wherein: said retaining means comprisesslide-bearing-surfaced elements carried on internal surfaces of saidstructure.
 6. A fixture, according to claim 3, further including: areplaceable retaining ring, carried by said piston, holding said sleevein position.
 7. A fixture, according to claim 3, wherein: said sleevehas a bore-hole formed through a side thereof, said bore-hole being inthroughgoing, communicating alignment with said vent port.
 8. A fixture,according to claim 5, wherein: said structure has a Pair of gussetsextending in parallel therefrom to facilitate a coupling of saidstructure to an ancilliary machine or device.
 9. In combination with atool having pressured-fluid discharging and intake ports, afluid-powered fixture for supporting and automatically moving the tool,comprising: an open-ended structure for slidably supporting the tool;means for engaging a surface of said tool, for slidably moving said toolrelative to said structure, having a fluid-pressure bearing surface, andbeing movable in response to a fluid pressuring of said bearing surface;and means coupling said surface-engaging means and said structuretogether; wherein said coupling means comprises guide means which,cooperative with said structure, guides the movement of said engagingmeans; said engaging means includes means for admitting pressured fluidto said bearing surface, and means for venting fluid therefrom, saidfluid admitting means being in throughgoing communication with saidintake port, and said fluid venting means being in throughgoingcommunication with said discharging port; and said guide means and saidengaging means cooperate to prevent venting of fluid from said bearingsurface until said engaging means has traveled a predetermined distance,and cooperatively and automatically vent fluid from said bearingsurface, via said fluid venting means, when said engaging means hastraveled said predetermined distance.
 10. a fixture, according to claim9, wherein: said engaging means comprises a cylinder having an externalsurface disposed for abutting engagement with said tool surface, and anelongated, walled cavity formed therein and closed at one end only; saidadmitting means and said venting means comprise an inlet port and a ventport, respectively, formed through the wall of said cavity; said guidemeans comprises a dowel-pin fixed at one end thereof to said structureand projecting therefrom into said cavity; said cylinder further havingsealing means disposed within said cavity cooperative with saiddowel-pin to close off said vent port.
 11. A fixture according to claim10, wherein: said sealing means comprises a sleeve interposed betweensaid dowel-pin and said cavity wall.
 12. A fixture, according to claim11, further including: a replaceable retaining ring, carried by saidcylinder, holding said sleeve in position.
 13. A fixture, according toclaim 11, wherein: said sleeve has a bore-hole formed through a sidethereof, said bore-hole being in throughgoing, communicating alignmentwith said vent port.
 14. A fixture, according to claim 9, wherein: saidstructure comprises slide-bearing-surfaced elements carried on internalsurfaces thereof for slidably retaining said tool therebetween.
 15. Afixture, according to claim 14, wherein: said structure has a pair ofgussets extending in parallel therefrom to facilitate a coupling of saidstructure to an ancilliary machine or device.
 16. In combination with afluid-powered tool having first means supplying pressured fluid theretofor enabling tool operation and second means for venting fluidtherefrom, a fluid-powered fixture for moving the tool and forcontrolling tool operation, comprising: means for engaging a surface ofsaid tool; said engaging means having a bearing surface responsive to afluid pressuring thereof to cause movement of said engaging means and,as a result, to effect movement of said tool; means interconnecting saidfirst means with said bearing surface and providing a first fluidcommunication therebetween; means effective for interconnecting saidsecond means with said bearing surface for providing a second fluidcommunication therebetween; and guide means fixed against movement,relative to said engaging means, for guiding movement of said engagingmeans and effective, in a first fixed position, relative to andcoincident with movement of said engaging means, for interdicting saidsecoNd fluid communication, and effective in a second fixed positionrelative to said engaging means upon movement of the latter, forautomatically accommodating said second fluid communication, said guidemeans guiding movement of said engaging means and enabling an operationof said tool when said guide means is in said first relative position,and halting said movement and operation when said guide means is in saidsecond relative position.